Persistence

Persistence is enabled by default. Disable it via super(defaults, { persist: false }).

Example:

protected override getPersistenceDriver(suffix?: string): PersistenceDriver {
  return new SessionStorageDriver(suffix)
}

See the Persistence service for available drivers and custom implementations: Persistence.

Notes:

• persistSuffix is passed to getPersistenceDriver(suffix) for namespacing.
• Persisted state is restored through a restore policy. By default, Blueprint restores only when the stored original matches your current defaults.
• persist: false disables automatic rehydration and background persistence.
• File/Blob values are not JSON-serializable and should use { persist: false }.

Default Restore Behavior

The built-in StrictPersistenceRestorePolicy behaves like this:

1. Blueprint asks the configured persistence driver for previously saved form state.
2. If no persisted state exists, the form starts from the constructor defaults.
3. If persisted state exists, Blueprint compares the persisted original value to the current constructor defaults.
4. If those values match, Blueprint restores:
   • the persisted form state
   • the persisted original
   • the persisted dirty flags
   • the persisted touched flags
5. If they do not match, Blueprint discards the persisted entry and starts from the constructor defaults.

The comparison ignores persistence-only markers used by PropertyAwareObject, so property-aware structures are compared by their actual form data.

Restore Policy

Override getPersistenceRestorePolicy() when a form needs custom restore behavior:

import {
  BaseForm,
  StrictPersistenceRestorePolicy,
  type PersistenceRestorePolicy
} from '@blueprint-ts/core/vue/forms'

export class MyForm extends BaseForm<RequestPayload, FormState> {
  protected override getPersistenceRestorePolicy(): PersistenceRestorePolicy<FormState> {
    return new StrictPersistenceRestorePolicy<FormState>()
  }
}

The default implementation already returns StrictPersistenceRestorePolicy, so you only need to override this method when a form needs a custom policy.

Debug Logging

Persistence debug logging is disabled by default. Enable it by overriding shouldLogPersistenceDebug():

export class MyForm extends BaseForm<RequestPayload, FormState> {
  protected override shouldLogPersistenceDebug(): boolean {
    return true
  }
}

When enabled, Blueprint logs:

• when no persisted state exists
• when persisted state is restored
• when persisted state is discarded and why

This is useful when debugging why a draft was not restored without enabling noisy logging for all forms.